Optical connector plug

ABSTRACT

In an optical connector plug, a front end of the shutter member can move between a shield position to shield a front end face of a ferrule in an extension state and a non-shield position to expose the front end face of the ferrule to the front side of a housing in a reduction state, when a plug frame and a shutter holding member move between the extension state and the reduction state. In the optical connector plug, in a course in which the shutter holding member is engaged with holding portions protruding in an axial direction of the optical connector adaptor and a grip member moves from the extension state to the reduction state, the front end of the shutter member is spaced to face front ends of the holding portions in the axial direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical connector plug that holdsfront ends of optical fibers and couples the optical fibers to eachother.

2. Description of the Related Art

In the related art, optical coupling between optical fibers used foroptical communication is performed using an optical connector. Theoptical connector includes optical connector plugs that hold front endsof optical fibers and an optical connector adapter that fix the opticalconnector plugs to each other and performs optical coupling of theoptical fibers.

As the optical connector, an SC-type optical connector (complying withIEC 61754-4) that couples the optical fibers to each other using aferrule barrel-shaped body (with the outer diameter of 2.5 mm) forholding the optical fibers or a miniaturized MU-type optical connector(complying with IEC 61754-6) using a ferrule barrel-shaped body (withthe outer diameter of 1.25 mm) for holding the optical fibers is used.

In recent years, Fiber To The Home (FTTH) that establishes a high speedcommunication environment using access networks formed by using opticalfibers and connecting subscriber lines from a telephone office to homesis spreading. In this optical fiber communication, an infrared ray witha wavelength of 1.3 μm to 1.55 μm is used as light for communication.Therefore, light output tends to increase.

However, if the high-output communication light is emitted from thefront ends of the optical fibers and a human body, particularly, a partsuch as eyes, is exposed to the communication light, there is a highpossibility of having a bad affect on the human body. In particular, ahigh safety is required for the optical connector plugs for holding thefront ends of the optical fibers led into households according to thespread of the FTTH to the households.

From this requirement, a structure of an optical connector plug thatincorporates a shutter to shield a front end face of the optical fiberis disclosed (for example, refer to Japanese Patent ApplicationLaid-Open (JP-A) No. 2005-292777 (page 22, FIG. 26)). The opticalconnector plug that incorporates the shutter is inserted into an opticalconnector adapter 110, the shutter is opened, and the front end of theoptical fiber is exposed, and the optical connector plug is coupled tothe optical connector adaptor 110.

In the optical connector plug that is disclosed in JP-A No. 2005-292777,an inner barrel (shutter holding member) contacts a coupling claw of theoptical connector adaptor, is pressed, and changes from an extensionstate to a reduction state. At this time, a shielding plate (shuttermember) is pushed down by a moving plug frame, a front end face of aferrule is exposed, and the optical connector plug is coupled to theoptical connector adapter.

However, although the coupling claw of the optical connector adapteroriginally pushes the inner barrel (shutter holding member), deformationmay be caused due to the pushing force, and the inner barrel (shutterholding member) may push the coupling claw and move to a center portionof the optical connector adaptor.

This is caused when the elastic force of the coupling claw of theoptical connector adaptor is weak, when an interval of the facingcoupling claws is more than a defined value, or when the opticalconnector plug is erroneously inserted with the inner barrel (shutterholding member).

As such, if the inner barrel (shutter holding member) moves to thecenter portion of the optical connector adaptor, the shielding plate(shutter member) is interposed between the ferrule and a sleeve holdingmember of the optical connector adaptor. In this state, if the opticalconnector plug is strongly inserted, the shielding plate (shuttermember) is deformed or the shielding plate is damaged.

Even when a shape corresponding to the coupling claw of the opticalconnector adaptor does not exist like when the optical connector plug isconnected to a measurer such as an optical power measurer and a feruleend face shape measurer or a ferrule end face cleaning tool is used, theshielding plate (shutter member) may be damaged.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, an optical connectorplug of a push-on coupling system includes a plug frame that holds aferrule having at least one optical fiber extending in an axialdirection and a housing that holds the plug frame therein. The housingincludes a grip member and a shutter holding member that move relativelyin an axial direction, the shutter holding member includes a shuttermember that has a front end positioned at the front side of the axialdirection and a base end positioned at the rear side of the axialdirection and held in the shutter holding member, the plug frame movesrelatively in the axial direction with respect to the shutter holdingmember while synchronizing with the grip member in a state in which apredetermined movement amount in the axial direction is allowed, havingan extension state in which the grip member moves to the rear side ofthe axial direction of the shutter holding member and a reduction statein which the grip member moves to the front side of the axial directionof the shutter holding member, the housing has a shape to be coupled tothe optical connector adaptor in the reduction state, and a couplingrecess portion that is provided on the outer circumference of the frontend side of the plug frame to be coupled to a coupling claw of theoptical connector adaptor.

In the optical connector plug according to the aspect of the presentinvention, the front end of the shutter member moves between a shieldposition to shield a front end face of the ferrule in the extensionstate and a non-shield position to expose the front end face of theferrule to the front side of the housing in the reduction state, whenthe plug frame and the shutter holding member move between the extensionstate and the reduction state. In the optical connector plug, in thecourse in which the shutter holding member is inserted with the holdingportions protruding in the axial direction of the optical connectoradaptor and the grip member moves from the extension state to thereduction state, the front end of the shutter member maintains spaced toface front ends of the holding portions in the axial direction.

In the optical connector plug according to the aspect of the presentinvention, in the shutter member, the base end is held at the rear sideof the axial direction of the shutter holding member and the front endis positioned at the center of the axial direction of the shutterholding member.

In the optical connector plug according to the aspect of the presentinvention, the front end of the shutter member is positioned to becloser to the rear side of the axial direction than the coupling recessportion of the plug frame, in the reduction state.

In the optical connector plug according to the aspect of the presentinvention, the shutter member is formed of a plate spring.

In the optical connector plug according to the aspect of the presentinvention, the shutter holding member is provided with a shutter biasingmember to bias the shutter member, to dispose the front end of theshutter member at the shield position in the extension state.

In the optical connector plug according to the aspect of the presentinvention, the optical connector plug has a shape that is coupled to anSC-type optical connector adaptor, in the reduction state.

In the optical connector plug according to the aspect of the presentinvention, even though the shutter holding member passes through thecoupling claw of the optical connector adaptor and moves to the centerportion of the optical connector adaptor, the shutter member does notinterfere with the sleeve holding portion. For this reason, an opticalconnector plug where the shutter member is not deformed and damaged canbe provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are perspective views of an optical connector plugaccording to an embodiment of the present invention;

FIGS. 2A to 2C are a front view and cross-sectional views of a main partof the optical connector plug according to the embodiment of the presentinvention;

FIGS. 3A to 3C are a front view and cross-sectional views of a main partof the optical connector plug according to the embodiment of the presentinvention;

FIG. 4 is an exploded perspective view of the optical connector plugaccording to the embodiment of the present invention;

FIG. 5 is an exploded perspective view of a cut part of an opticalconnector adapter according to the embodiment of the present invention;

FIGS. 6A and 6B are cross-sectional views illustrating a couplingoperation between the optical connector plug and the optical connectoradapter according to the embodiment of the present invention; and

FIGS. 7A and 7B are cross-sectional views illustrating a couplingoperation between the optical connector plug and the optical connectoradapter according to the embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described in detail on thebasis of an embodiment.

[First Embodiment]

FIGS. 1A and 1B are perspective views of an optical connector plug 10according to an embodiment of the present invention and FIGS. 2A to 3Care front views, cross-sectional views taken along the line A-A′, andcross-sectional views taken along the line B-B′ of the optical connectorplug 10. FIG. 4 is an exploded perspective view of the optical connectorplug 10.

As illustrated in FIGS. 1A to 4, the optical connector plug 10 accordingto this embodiment has a shape in which the optical connector plug 10can be coupled to an SC-type optical connector adaptor to be describedbelow. The optical connector plug 10 includes a housing 20, a plug frame30 that is held movably in an axial direction (toward the front side andthe rear side of an axial direction) in the housing 20, a ferrule 40that holds an optical fiber 15 for optical coupling and is inserted fromthe rear of the plug frame 30, a stop ring 50 that has a front endengaged with a rear end of the plug frame 30, and a biasing spring 60that is held between the ferrule 40 and the stop ring 50 for biasing theferrule 40 toward the front of the axial direction.

As illustrated in FIGS. 2A to 2C, the ferrule 40 includes a ferrulebarrel-shaped body 41 that has the outer diameter of 2.499 mm and acollar member 42 that is fitted into one end of the ferrulebarrel-shaped body 41.

The ferrule barrel-shaped body 41 has a substantially cylindrical shape.In an inner portion of the ferrule barrel-shaped body 41, insertion hole41 a that is formed to be penetrated in the axial direction and holdsthe optical fiber 15 inserted therein is provided. At the rear end ofthe optical fiber insertion hole 41 a, a tapered portion 41 b of whichthe inner diameter increases gradually toward an opening side isprovided. By providing the tapered portion 41 b, the tapered portion 41b prevents the front end of the optical fiber 15 from being chipped orbent due to the contact of the front end of the optical fiber 15 with anend face of the ferrule barrel-shaped body 41, when the optical fiber 15is inserted into the optical fiber insertion hole 41 a.

The ferrule barrel-shaped body 41 may be made of a ceramic material suchas zirconia, a plastic material, and a glass material such ascrystallized glass, borosilicate glass, and quartz. In this embodiment,the ferrule barrel-shaped body 41 is made of zirconia and the outerdiameter of the ferrule barrel-shaped body 41 is 2.499 mm.

In addition, in the collar member 42 that is fitted into the rear end ofthe ferrule barrel-shaped body 41, an optical fiber core wire insertionhole 42 a that holds an optical fiber core wire 16, which is coated onthe outer circumference of the optical fiber 15 along the axialdirection, inserted therein, and a collar portion 43 that protrudes by apredetermined amount in a radius direction along a circumferentialdirection of the outer circumference are provided.

As illustrated in FIG. 4, on the outer circumference of the collarportion 43, key grooves 44 are provided in two or four places at aninterval of 90 degrees in the circumferential direction. The key grooves44 have the same width along the axial direction. As the key grooves 44are engaged with a key groove protruding portion 32 a of the plug frame30, movement of the ferrule 40 in a rotating direction with an axiscentered with respect to the plug frame 30 is regulated.

The number, position, depth and shape of the key grooves 44 are notparticularly limited and may be appropriately set according to the plugframe 30 to position the ferrule 40.

In addition, a material of the collar member 42 is not particularlylimited and may include a metal material such as stainless steel, brass,or iron, or a resin material such as plastic. In this embodiment, thecollar member 42 is made of the stainless steel.

As illustrated in FIGS. 2A to 2C, the plug frame 30 has a shape of ahollow rectangular pillar shape. In the plug frame 30, the ferrule 40that is penetrated along the axial direction and a ferrule insertionhole 31 that can insert the spring 60 therein are provided. In theferrule insertion hole 31, a ferrule protruding hole 32 is provided toprotrude only the front end of the ferrule barrel-shaped body 41. Theferrule protruding hole 32 has the outer diameter that is larger thanthat of the ferrule barrel-shaped body 41 and the inner diameter that issmaller than that of the collar portion 43.

In the ferrule insertion hole 31, the two key groove protruding portions32 a that are engaged with the key grooves 44 of the ferrule 40 areprovided to protrude to the inner side of the radius direction. As thekey groove protruding portion 32 a are engaged with the key grooves 44of the ferrule 40, movement of the ferrule 40 in a rotating directionwith an axis centered with respect to the plug frame 30 is regulated andthe ferrule 40 is held to be movable in the axial direction.

As illustrated in FIGS. 2B and 2C, engagement holes 33 that are openedto the outer circumference in communication with the ferrule insertionhole 31 are provided on two facing surfaces of the outer circumferenceof the plug frame 30, respectively. As an engagement protrusion portion54 provided on the outer circumference of the stop ring 50 is engagedwith the engagement holes 33, the plug frame 30 is engaged with the stopring 50.

In addition, on the two facing surfaces crossing a surface in which theengagement holes 33 of the plug frame 30 are provided, a cut portion 34that is cut by a predetermined length toward the axial direction fromthe rear end is provided, as illustrated in FIG. 4. The cut portion 34facilitates elastic deformation of the plug frame 30 to open the plugframe 30 outward, when the stop ring 50 is engaged with the rear end ofthe plug frame 30.

In addition, a pair of coupling recess portions 35 that are recessedfrom an outer surface of the plug frame 30 to the inner side of theradial direction are provided at the centers of the two facing surfacesof the outer circumference of the plug frame 30 in the axial direction,respectively. The coupling recess portions 35 of the plug frame 30 arecoupled to a locking claw 135 a provided on a front end of a couplingclaw 135 of the optical connector adapter 110 to couple the opticalconnector adapter 110 and the optical connector plug 10.

As illustrated in FIGS. 2A to 2C, the stop ring 50 that is engaged withthe rear end of the plug frame 30 has a cylindrical shape that is madeof a metal material or a resin material such as plastic, and has anoptical fiber core wire insertion hole 51 into which the optical fibercore wire can be inserted. A communication hole 52 into which the spring60 can be inserted is provided at the side of a front end of the opticalfiber core wire insertion hole 51. A stepped portion 53 that is formedby the difference of the inner diameters between the optical fiber corewire insertion hole 51 and the communication hole 52 is provided.

The spring 60 is held in the communication hole 52 and the side of therear end of the collar member 42 of the ferrule 40 is inserted into theheld spring 60. One end of the spring 60 contacts a rear end face of thecollar portion 43 and the other end contacts the stepped portion 53 ofthe stop ring 50. As a result, the ferrule 40 is held in a state inwhich the ferrule 40 is biased forward with respect to the plug frame30. At this time, the ferrule 40 is biased and held in a state in whichthe front end face of the collar portion 43 contacts a ferruleprotrusion portion hole 32 and the forward movement is regulated.

As described above, as the key groove 44 of the collar portion 43 of theferrule 40 is engaged with the key groove protruding portion 32 a of theferrule insertion hole 31, the movement of the ferrule 40 in therotating direction around the axis is regulated and the ferrule 40 isheld to be movable in the axial direction. For this reason, the ferrule40 is biased and held to be movable toward the rear side, in a state inwhich the movement of the ferrule 40 in the rotating direction withrespect to the plug frame 30 is regulated.

On the outer circumference of the front side of the stop ring 50, twoengagement protrusion portions 54 that protrude into the engagement hole33 of the plug frame 30 are provided at facing positions. The engagementprotrusion portions 54 have outer circumferential surfaces having ashape of a taper where its outer diameter decreases gradually toward itsfront end. The engagement protrusion portions 54 are engaged with theengagement hole 33 of the plug frame 30 while pushing the rear end ofthe plug frame 30 to the outside, when the stop ring 50 is inserted fromthe rear side of the plug frame 30.

To the side of the rear end of the stop ring 50, a caulking ring 57 isfixed. The caulking ring 57 is pressed and fixed to the rear end of thestop ring 50, in a state in which a tension member 17 of an opticalfiber cord 19 is interposed between the stop ring 50 and the caulkingring 57. The tension member 17 is disposed in an internal space of anouter cover 18, on the outer circumference of the coated optical fibercore wire 16 coated on the outer circumference of the optical fiber 15.

To the rear end of the caulking ring 57, a ring 58 is fixed. The ring 58is pressed and fixed to the rear end of the caulking ring 57, in a statein which the outer cover 18 of the optical fiber cord 19 is interposedbetween the caulking ring 57 and the ring 58. The optical fiber cord 19is fixed to the optical connector plug 10, by the stop ring 50, thecaulking ring 57, and the ring 58.

In addition, a boot 59 that includes the caulking ring 57 and the ring58 inside is fitted into the rear side of the stop ring 50. The opticalfiber cord 19 is inserted into the boot 59. The boot 59 is formed of anelastic material such as rubber or elastomer or a resin material such asplastic.

Meanwhile, as illustrated in FIGS. 2A to 3C, the housing 20 includes agrip member 21 that has a shape of a hollow rectangular pillar and ashutter holding member 22 that has a shape of a hollow rectangularpillar and is accommodated to be movable to the front and rear sides ofthe axial direction in the grip member 21. The housing 20 has areduction state in which the shutter holding member 22 is accommodatedin the grip member 21, as illustrated in FIG. 3A to 3C, and an extensionstate in which the shutter holding member 22 protrudes to the frontside, as illustrated in FIGS. 2A to 2C.

As illustrated in FIGS. 2A to 3C, a holding hole 23 that holds a biasingmember receiving member 95 therein is provided in the grip member 21.The biasing member receiving member 95 is engaged with and held in theholding hole 23 to move by the predetermined amount with respect to thegrip member 21. More specifically, an engagement window 24 that engageswith an engagement convex portion 96 provided on the outer circumferenceof the biasing member receiving member 95 is provided at the rear endside of the holding hole 23. A rear surface of the engagement convexportion 96 of the biasing member receiving member 95 contacts a rearsurface of the engagement window 24 and movement of the biasing memberreceiving member 95 to the rear side is regulated. In addition, acontact surface 97 of the biasing member receiving member 95 contacts acontact step 23 a that is an inner surface of the holding hole 23 andmovement of the biasing member receiving member 95 to the front side isregulated. The biasing member receiving member 95 is connected to theplug frame 30 through the stop ring 50. The front and rear movementamounts that are allowed by the plug frame 30 with respect to the gripmember 21 are equal to the front and rear movement amounts that areallowed by the biasing member receiving member 95 with respect to thegrip member 21.

The biasing member receiving member 95 has a first biasing memberholding portion 154 of an approximately cylindrical shape that has thepredetermined length and extends in the axial direction and a secondbiasing member holding portion 155 that is positioned at the outside ofa circumferential direction of the first biasing member holding portion154 and extends in the axial direction. In the biasing member receivingmember 95, the first biasing member holding portion 154 and the secondbiasing member holding portion 155 are inserted into the holding hole 23of the grip member 21. A front end of the boot 59 is inserted into thefirst biasing member holding portion 154 to be removable.

As illustrated in FIGS. 2A to 3C, a biasing member 90 is providedbetween the biasing member receiving member 95 and the shutter holdingmember 22 in the grip member 21. The biasing member 90 biases theshutter holding member 22 in a direction pushing the shutter holdingmember 22 to the front side. The biasing member 90 is composed of a coilspring that is made of a metal material such as stainless steel or pianowire and extends in the axial direction. In this embodiment, the coilspring that is made of the stainless steel is used. The spring forcethat pushes the shutter holding member 22 to the front side by thebiasing member 90 is suppressed to the magnitude not disturbinginsertion of the optical connector plug 10 into the optical connectoradaptor 110 and has the magnitude that is sufficient to securely pushthe shutter holding member 22 to make the housing 20 become an extensionstate. Specifically, the spring force has the magnitude in a range of0.5 to 4 N.

The coil spring that is the biasing member 90 is positioned at the outerside of an outer circumferential surface of the first biasing memberholding portion 154 of the biasing member receiving member 95 and ispositioned at the inner side of an inner circumferential surface of thesecond biasing member holding portion 155. That is, the coil spring issupported to the biasing member receiving member 95, in a state in whichthe coil spring is interposed between the first biasing member holdingportion 154 and the second biasing member holding portion 155. Thereby,inadvertent falling of the coil spring from the holding hole 23 of thegrip member 21 can be prevented. The inner diameter of the coil springthat is the biasing member 90 is slightly larger than the outer diameterof the first biasing member holding portion 154.

The biasing member 90 and the biasing member receiving member 95 havethe inner diameters that are larger than the outer diameters of thecaulking ring 57 and the optical fiber cord 19. The biasing member 90and the biasing member receiving member 95 are disposed on the outercircumference of the caulking ring 57 to overlap each other. In thisembodiment, the biasing member 90 is configured using a coil spring thathas the coil inner diameter equal to φ7.0 or more and equal to φ7.4 orless.

Thereby, when the optical connector plug 10 is assembled, after pressingand fixing the caulking ring 57 to the rear end side of the stop ring 50with the tension member 17 of the optical fiber cord 19 therebetween,the biasing member 90 and the biasing member receiving member 95 passingthrough the upper side of the optical fiber cord 19 of the rear side aremoved to the front side, the biasing member receiving member 95 isconnected to the stop ring 50, and the biasing member receiving member95 is engaged with the grip member 21.

As illustrated in FIGS. 3B and 4, in a region of the grip member 21 thatfaces the coupling recess portions 35 of the plug frame 30, a firstexposure hole 25 that exposes the coupling recess portion 35 to theoutside is provided. In addition, a coupling releasing portion 25 a thatis inclined toward the rear end side of the grip member 21 is providedon a side of a surface on which the first exposure hole 25 is opened tothe outside. The coupling releasing portion 25 a releases coupling ofthe coupling claw 135 and the coupling recess portion 35 as the couplingclaw 135 is pressed according to the movement of the grip member 21 tothe rear side by drawing out the grip member 21, under a state in whichthe coupling claw 135 of the optical connector plug 110 is coupled tothe coupling recess portion 35 of the plug frame 30.

As illustrated in FIGS. 1A and 1B and 2B, a key 26 that protrudes toposition the optical connector plug 10 in the rotating direction aroundan axis with respect to the optical connector adapter 110 when theoptical connector plug 10 is coupled to the optical connector adapter110 is provided on the outer circumference of one side of an facingsurface in which the first exposure hole 25 of the grip member 21 is notprovided. On a surface of the same direction as the key 26 of the gripmember 21 on the outer circumference of the shutter holding member 22, adisplay portion 28 is provided to easily recognize the same direction asthe surface where the key 26 is provided.

As illustrated in FIGS. 2A to 2C and 4, in the shutter holding member 22that is provided to be movable to the front and rear sides of the axialdirection in the grip member 21, an insertion hole 22 a where the plugframe 30 is moved to the front and rear sides along the axial directionis provided. On an outer circumferential surface of the rear end side ofthe shutter holding member 22, a protruded disengagement preventionprotrusion portion 22 b is provided. The disengagement preventionprotrusion portion 22 b contacts a stepped portion 105 provided on aninner surface of the grip member 21 and movement of the disengagementprevention protrusion portion 22 b in a disengagement direction isregulated. The disengagement prevention protrusion portion 22 b isformed in a tapered shape in which the thickness decreases toward therear side of the shutter holding member 22. When the grip member 21 andthe shutter holding member 22 are assembled, the disengagementprevention protrusion portion 22 b is accommodated beyond the steppedportion 105 of the grip member 21 by inserting the shutter holdingmember 22 into the grip member 21. Accordingly, the shutter holdingmember 22 is prevented from being disengaged from the grip member 21.

The amount of movement of the plug frame 30 with respect to the gripmember 21 is not particularly limited as long as the optical connectorplug 10 can be disengaged from the optical connector adapter 110. Forexample, in the case of using the SC-type optical connector adapter 110,the plug frame 30 may be moved by about 2 mm in the axial direction(anteroposterior direction) with respect to the grip member 21.

A second exposure hole 29 that exposes the coupling recess portion 35 ofthe plug frame 30 to the outside in communication with the firstexposure hole 25 of the grip member 21 when the housing 20 is in areduction state is provided at the front end side of the shutter holdingmember 22. That is, the housing 20 is coupled to the coupling claw 135of the optical connector adapter 110 as the coupling recess portion 35of the plug frame 30 is exposed by the first and second exposure holes25 and 29 in the reduction state in which the shutter holding member 22is accommodated in the grip member 21.

On the front end side of the shutter holding member 22, a coupling clawpassing portion 27 through which the coupling claw 135 of the opticalconnector plug 110 can pass without no catch is formed. Thereby, whenthe optical connector plug 10 is inserted into the optical connectoradaptor 110, the shutter holding member 22 can be moved to a centerportion of the optical connector adaptor 110 without contacting thecoupling claw 135.

In the shutter holding member 22, a shutter member 70 that is held to beinclined and deformed through a base end 72 on one surface 22 c of theinsertion hole 22 a is provided.

The shutter member 70 is formed of a plate member that almost entirelycloses the insertion hole 22 a. The base end 72 of the shutter member 70is held on one surface 22 c that is one of the two facing surfaces wherethe second exposure hole 29 is not provided. A front end 71 of theshutter member 70 is provided to be inclined or deformed toward theother surface 22 d opposite to one surface 22 c where the base end 72 isheld. The front end 71 of the shutter member 70 is provided to bepositioned closer to the front side of the housing 20 than the base end72, when the front end 71 moves to one surface 22 c where the base end72 is held. The shutter member 70 has the length where the front end 71contacts the other surface 22 d at a predetermined inclination angle,when the front end 71 is inclined and deformed toward the side of theother surface 22 d.

The shutter member 70 closes the insertion hole 22 a as the front end 71thereof contacts the other surface 22 d of the insertion hole 22 a. Asthe front end 71 of the shutter member 70 moves to one surface 22 c, theshutter member 70 allows the movement of the plug frame 30 and exposes afront end face of the ferrule 40 to the front side. The shutter member70 is inclined and deformed between a shield position to shield thefront end face of the ferrule 40 and a non-shield position to expose thefront end face of the ferrule 40 to the front side.

The shutter member 70 is provided not to interfere with the ferrule 40and the plug frame 30 at the shield position. The shutter member 70 isprovided such that the shutter member 70 contacts members such as afirst holding portion 132 (holding portion), a second holding portion145 (holding portion), and the coupling claw 135 of the opticalconnector adaptor 110 described below and is not deformed and destroyed,when the optical connector plug 10 is connected to the optical connectoradaptor 110.

As illustrated in FIGS. 3A to 3C, at the non-shield position that iscoupled to the optical connector adaptor 110, the front end 71 of theshutter member 70 is positioned to be closer to the rear side of theaxial direction than the coupling recess portion 35 of the plug frame30. This is because the first holding portion 132 or the second holdingportion 145 of the optical connector adaptor 110 is positioned to becloser to the center side of the optical connector 110 (front side ofthe axial direction of the optical connector plug 10) than the lockingclaw 135 a of the coupling claw 135.

Therefore, even though the shutter member 70 is inclined and deformedbetween the shield position and the non-shield position in a state inwhich the shutter holding member 22 moves to the center portion of theoptical connector plug 110, the shutter member 70 is not deformed ordestroyed.

A material of the shutter member 70 is not particularly limited as longas it has durability. For example, the material may include a metalmaterial such as stainless steel. In this embodiment, as the shuttermember 70, the stainless steel that has spring elasticity is used. Inthis embodiment, when the plug frame 30 moves to the rear side of theaxial direction and the housing 20 becomes an extension state, the frontend 71 is biased to the side of the other surface 22 d by the springelasticity of the shutter member 70 and is moved to the shield position.

The shutter member 70 may include a unit that shields the front end faceof the ferrule 40 and a unit that biases the front end 71 to the side ofthe other surface 22 d. For example, the shutter member 70 includes ashutter plate where the base end 72 is held on one surface 22 c to beinclined and rotated and the front end 71 is inclined to contact theother surface 22 d and a torsion spring that is provided on one surface22 c and biases the front end 71 of the shutter plate 70 to the othersurface 22 d.

In this embodiment, an accommodating portion 22 e that accommodates theshutter member 70 is provided on one surface 22 c of the insertion hole22 a of the shutter holding member 22, such that the shutter member 70does not regulate the movement of the plug frame 30 in contact with theplug frame 30 when the shutter member 70 moves to the non-shieldposition.

As illustrated in FIGS. 2A to 2C, in the optical connector plug 10 thathas the above configuration, the housing 20 becomes an extension stateand the shutter member 70 is inclined and deformed to the shieldposition. Thereby, the shutter member 70 shields the front end face ofthe ferrule 40 such that light is not emitted from the front end of theoptical connector plug 10.

As illustrated in FIGS. 3A to 3C, by making the housing 20 become thereduction state, a front end frame portion 39 of the plug frame 30 laysthe shutter member 70 and the shutter member 70 is accommodated in theaccommodating portion 22 e and is inclined and deformed to thenon-shield position. Thereby, the shutter member 70 does not shield thefront end face of the ferrule 40 and the optical fibers 15 are opticallycoupled. The extension state and the reduction state of the housing 20can be changed by grasping the grip member 21 and attaching/detaching itto/from the optical connector adapter 110.

Here, the optical connector adapter 110 to which the optical connectorplug 10 according to this embodiment is coupled will be described. FIG.5 is an exploded perspective view of a cut portion of the opticalconnector adapter 110.

As illustrated in FIG. 5, the optical connector adapter 110 to which theoptical connector plug 10 is coupled is of an SC type and has an opticalcoupling sleeve 120 and a holding member 150. The holding member 150includes a sleeve holder 130 and an outer member 140 that interpose theoptical coupling sleeve 120 therebetween.

The optical coupling sleeve 120 has a cylindrical shape, is formed ofmetal or ceramic, and is provided with a slit 121 penetrated along theaxial direction. The optical coupling sleeve 120 has the inner diameterslightly smaller than the outer diameter of the ferrule barrel-shapedbody 41 of the optical connector plug 10 for holding the optical fiber.The optical coupling sleeve 120 closely adheres and holds the ferrulebarrel-shaped body 41 to an inner surface of the optical coupling sleeve120 in a facing and coupling state by elastic deformation by the slit121. In this embodiment, since the ferrule barrel-shaped body 41 has theouter diameter of 2.499 mm, the optical coupling sleeve 120 has theinner diameter of φ2.495 mm and the outer diameter of φ3.0 to 3.2 mm.

The sleeve holder 130 of the holding member 150 that holds the opticalcoupling sleeve 120 has a first holding portion 132 of a cylindricalshape that has a first through-hole 131 to hold one end of the opticalcoupling sleeve 120. A first stopper protrusion portion 133 that locksone end of the optical coupling sleeve 120 is protruded inward in aradial direction at the one end of the first holding portion 132 in alongitudinal direction.

A first flange portion 134 of a rectangular shape is provided on theouter circumference of the other end of the first holding portion 132opposite to the first stopper protrusion portion 133.

At both short sides of the first flange portion 134, a pair of lockingclaws 135 are provided to interpose the first holding portion 132therebetween and a pair of coupling claws 135 are provided to interposethe second holding portion 145 of the outer member 140 to be describedbelow. In the front ends of the coupling claws 135, the pair of lockingclaws 135 a is provided to face each other, respectively. The couplingclaws 135 couple the optical connector plug 10 with the opticalconnector adapter 110 by coupling with the coupling recess portion 35 ofthe plug frame 30 of the optical connector plug 10. A pair of lockingprotrusion portions 137 is provided at an end of a short side of thefirst flange portion 134.

Meanwhile, the outer member 140 of the holding member 150 has apenetrating portion 141 that is a through-hole that holds the sleeveholder 130 therein. A groove portion 143 that is fitted with the end ofthe first flange portion 134 of the sleeve holder 130 is provided atboth short sides of the penetrating portion 141. A second flange portion144 contacting the first flange portion 134 and a second holding portion145 having a cylindrical portion are provided at a side opposite to aninsertion direction of the first flange portion 134 from an axial centerportion within the penetrating portion 141. The second holding portion145 extends in the axial direction from the second flange portion 144and communicates with the first through-hole 131. In the second holdingportion 145, a second through-hole 142 that holds the other end of theoptical coupling sleeve 120 is provided. A second stopper protrusionportion 146 that locks the end of the optical coupling sleeve 120protrudes inward in the radial direction at the end of the secondholding portion 145.

Meanwhile, a fixation flange 148 is provided in the axial center portionof the outer circumferential surface at both short sides of the outermember 140. A fixation groove 148 a to fix the housing 140 to a panel(not illustrated in the drawings) through screwing is provided in thefixation flange 148. A plate concave portion 149 is formed at the facingshort sides of one side of the housing 140 in the axial direction and asurface between the facing short sides. A U-shaped plate 153 having ametal coupling claw 152 is fitted into the plate concave portion 149.

A sequence of when the optical connector adapter 110 according to thisembodiment described above is assembled is as follows. The sleeve holder130 is inserted in the outer member 140 with the optical coupling sleeve120 inserted between the first and second holding portions 132 and 145,and a locking pin 151 is inserted into the outer member 140 such that anarm portion 151 a is engaged with the locking protrusion portion 137 ofthe sleeve holder 130. Accordingly, the sleeve holder 130 is engagedwith the outer member 140 and the optical coupling sleeve 120 isinterposed between the sleeve holder 130 and the housing 140.

Hereinafter, an operation of coupling the optical connector plug 10 tothe optical connector adapter 110 will be described in detail. FIGS. 6Ato 7B are cross-sectional views illustrating a coupling operation of theoptical connector. FIG. 6B is a cross-sectional view taken along theline C-C′ of FIG. 6A. FIG. 7B is a cross-sectional view taken along theline C-C′ of FIG. 7A.

As illustrated in FIGS. 6A and 6B, the front end 157 of the holdingportion 132 and the front end 71 of the shutter member 70 face in theaxial direction, when the shutter holding member 22 is engaged with theholding portion 132 protruding in the axial direction of the opticalconnector adaptor 110, in the extension state of the housing 20. Thatis, the front end 72 of the shutter member 70 is fixed to the rear sideof the axial direction of the shutter holding member 22 and the frontend 71 of the shutter member 70 is positioned at the center of the axialdirection of the shutter holding member 22. As illustrated in FIGS. 6Aand 6B, the grip member 21 of the optical connector plug 10 is graspedand inserted into the penetrating portion 141 of the optical connectoradapter 110 under a state in which the housing 20 extends and the frontend of the ferrule 40 is shielded by the shutter member 70. At thistime, the coupling claw 135 passes through a coupling claw passingportion 27, the shutter holding member 22 moves to the center portion ofthe optical connector adaptor 110 without contacting the coupling claw135, and a front end face 22 f of the shutter holding member 22 contactsthe first flange portion 134.

If the optical connector plug 10 is inserted, at the same time as whenthe shutter holding member 22 presses and reduces the biasing member 90,a front end edge 39 of the plug frame 30 that is moved to the front endof the axial direction together with the grip member 21 lays the shuttermember 70, and the shutter member 70 is accommodated in theaccommodating portion 22 e. That is, by only inserting the opticalconnector plug 10 into the optical connector adaptor 110, the housing 20is reduced gradually from the extension state to the reduction state andthe shutter member 70 is inclined and deformed from the shield positionto the non-shield position. In the optical connector plug 10, in acourse in which the shutter holding member 22 is engaged with theholding portions 132 and 145 protruding in the axial direction of theoptical connector adaptor 110 and the grip member 21 moves from theextension state to the reduction state, the front end 71 of the shuttermember 70 is spaced to face the front ends 157 of the holding portions132 and 145 in the axial direction.

At the same time as when the state of the housing 20 changes graduallyto the reduction state, the plug frame 30 moves to the center portion ofthe optical connector adaptor 110 while increasing the interval of thefacing coupling claws 135, and the coupling recess portion 35 of theplug frame 30 is exposed to the outside by the first and second exposureholes 25 and 29 of the housing 20. At the same time, the ferrule 40 isinserted into the optical coupling sleeve 120.

As illustrated in FIGS. 7A, and 7B, the locking claw 135 a of theoptical connector adaptor 110 is coupled to the coupling recess portion35 through the first and second exposure holes 25 and 29. Thereby, theoptical connector plug 10 is coupled to the optical connector adaptor110. Although not illustrated in the drawings, one optical connectorplug 10 is connected from the other side of the optical connectoradaptor 110 in the same way and the optical connector plugs 10 areoptically coupled through the optical connector adaptor 110.

As such, by only inserting the optical connector plug 10 into theoptical connector adaptor 110, the housing 20 becomes the reductionstate and the shutter member 70 moves to the non-shield position. Duringa series of operations until the optical connector plugs 10 are insertedinto the optical connector adaptor 110 and are connected, the ferrule 40is not exposed to the outside of the housing 20. For this reason,communication light does not leak into the outside of the opticalconnector plug 10 and the optical connector plug 10 has high safety.

Meanwhile, if the grip member 21 of the optical connector plug 10 isgrasped and drawn out of the optical connector adapter 110, the gripmember 21 is retreated from the plug frame 30, the coupling claw 135 ispressed by the coupling releasing portion 25 a, and the locking claw 135a of the coupling claw 135 is disengaged from the coupling recessportion 35. Thereby, the plug frame 30 is retreated. At the same time,the shutter holding member 22 is pressed to the front side by thebiasing member 90 and the housing 20 extends gradually from thereduction state to the extension state.

Thereby, the shutter member 70 that is accommodated in the accommodatingportion 22 c by the plug frame 30 begins to be inclined and deformedtoward the shield position. The optical connector plug 10 is detachedfrom the optical connector adaptor 110, the housing 20 becomes theextension state, the shutter member 70 is inclined and deformed to theshield position, and the front end 71 of the shutter member 70 contactsthe inner surface of the insertion hole 22 a. As a result, the shuttermember 70 is positioned at the shield position and shields the front endface of the ferrule 40.

In cooperation with the operation of inserting the optical connectorplug 10 according to this embodiment into the optical connector adaptor110 and the operation of drawing the optical connector plug 10 from theoptical connector adaptor 110, the front end 71 of the shutter member 70moves to the shield position and the non-shield position. Therefore,connection with the optical connector adaptor 110 is easy.

In a state in which the front end 71 of the shutter member 70 movesbetween the shield position and the non-shield position, the shuttermember 70 does not interfere (contact and collide) with the opticalconnector adaptor 110. Therefore, the shutter member 70 is not deformedand damaged. For this reason, even when the elastic force of thecoupling claw 135 of the optical connector adaptor 110 becomes weak,when the interval of the coupling claws 135 is larger than the standardinterval, and the shutter holding member 22 of the optical connectorplug 10 is erroneously inserted into the optical connector adaptor 110,the optical connector 10 can be inserted and drawn.

Even when the optical connector plug 10 is inserted into a portion nothaving a shape corresponding to the coupling claw 135 of the opticalconnector adaptor 110 like when the optical connector plug 10 isconnected to a measurer such as an optical power measurer and a ferruleend face shape measurer or is inserted into a ferrule end face cleaningtool, the shutter member 70 can be attached/detached without a damageand convenience can be raised.

Even in a state in which the optical connector plug 10 is not connectedto the optical connector adaptor 110, the biasing member 90 (coilspring) biases the housing 20 in the extension state at all times.Therefore, the shutter member 70 can be prevented from becoming thereduction state erroneously and moving to the non-shield position andsafety can be raised.

In the optical connector plug 10, by providing the biasing memberreceiving member 95, the difficulty of assembling the optical connectorplug can be removed, the biasing member 90 (coil spring) and the biasingmember receiving member 95 can be disposed on the outer circumference ofthe caulking ring 57, and the entire length of the optical connectorplug 10 can be reduced.

REFERENCE SIGNS LIST

-   10: optical connector plug-   15: optical fiber-   20: housing-   21: grip member-   22: shutter holding member-   30: plug frame-   35: coupling recess portion-   40: ferrule-   41: ferrule barrel-shaped body-   50: stop ring-   57: caulking ring-   58: ring-   59: boot-   60: spring-   70: shutter member-   71: front end-   72: base end-   90: biasing member-   95: biasing member receiving member-   110: optical connector adaptor-   120: optical coupling sleeve-   130: sleeve holder-   135: coupling claw-   140: outer member-   150: holding member-   151: locking pin-   153: plate-   154: first biasing member supporting portion-   155: second biasing member supporting portion-   157: front end

What is claimed is:
 1. An optical connector plug of a push-on couplingsystem, which is coupled to an SC- type optical connector adaptor,complying with IEC 61754-4, having (1) an optical coupling sleeve, (2) aholding member, and (3) a flange portion provided on the outercircumference of an end of the holding portion , wherein the holdingmember includes a holding portion to hold one end of an optical couplingsleeve protruding in an axial direction and a pair of coupling claws tocouple the optical connector plug by coupling with a coupling recessportion of the optical connector plug, the optical connector plugcomprising: (a) a plug frame that holds a ferrule having at least oneoptical fiber extending in an axial direction; and (b) a housing thatholds the plug frame therein, wherein the housing includes a grip memberand a shutter holding member that move relatively in the axialdirection, the shutter holding member includes a shutter member that hasa front end positioned at a front side in the axial direction and a baseend positioned at a rear side in the axial direction and held in theshutter holding member, the plug frame moves relatively in the axialdirection with respect to the shutter holding member while synchronizingwith the grip member in a state in which a predetermined movement amountin the axial direction is allowed, having an extension state in whichthe grip member moves to the rear side of the axial direction of theshutter holding member and a reduction state in which the grip membermoves to the front side of the axial direction of the shutter holdingmember, the housing has a shape to be coupled to the optical connectoradaptor in the reduction state, and a coupling recess portion providedon the outer circumference of a front end side of the plug frame toreceive therein the coupling claw of the optical connector adaptor,characterized in that, after the front end of the shutter holding memberis inserted toward the holding portion protruding in an axial directionof the optical connector adaptor, the front end of the shutter holdingmember passes through the coupling claw of the optical connectoradaptor, moves to a center of the optical connector adaptor and thencontacts the flange portion, and then, the front end of the shuttermember moves from a shield position to shield a front end face of theferrule in the extension state to a non-shield position to expose thefront end face of the ferrule to a front side of the housing in thereduction state, and movement of the front end of the shutter memberinto the non-shield position does not contact the holding portion. 2.The optical connector plug according to claim 1, wherein, in the shuttermember, the base end is held at a rear side of the axial direction ofthe shutter holding member and the front end is positioned at a centerof the axial direction of the shutter holding member.
 3. The opticalconnector plug according to claim 2, wherein the front end of theshutter member is positioned to be closer to the rear side of the axialdirection of the shutter holding member than the coupling recess portionof the plug frame, in the reduction state.
 4. The optical connector plugaccording to claim 1, wherein the shutter member is formed of a platespring.
 5. The optical connector plug according to claim 1, wherein theshutter holding member is provided with a shutter biasing member to biasthe shutter member and to dispose the front end of the shutter member atthe shield position in the extension state.
 6. A push-on coupling systemcomprising the optical connector plug according to claim 1 and anoptical connector adaptor; wherein the optical connector adaptorcomplies with IEC 61754-4 and comprises of: (a) an optical couplingsleeve, (b) a holding member including, a holding portion to hold oneend of an optical coupling sleeve protruding in an axial direction, (c)a flange portion provided on the outer circumference of an end of theholding portion, and (d) a pair of coupling claws to couple the opticalconnector plug by coupling with a coupling recess portion of the opticalconnector plug, characterized in that, when the shutter holding memberis inserted toward a holding portion protruding in an axial direction ofthe optical connector adaptor, the insertion causing the front end ofthe shutter holding member to pass through the coupling claw of theoptical connector adaptor and to move to a center of the opticalconnector adaptor and then to contact the flange portion, the front endof the shutter member is spaced to the rear side in the axial directionfrom both the front end of the shutter member and the holding portion ofthe optical connector adaptor.
 7. The push-on coupling system accordingto claim 6, wherein, in the shutter member, the base end is held at arear side of the axial direction of the shutter holding member and thefront end is positioned at a center of the axial direction of theshutter holding member.
 8. The push-on coupling system according toclaim 7, wherein the front end of the shutter member is positioned to becloser to the rear side of the axial direction of the shutter holdingmember than the coupling recess portion of the plug frame, in thereduction state.
 9. The push-on coupling system according to claim 6,wherein the shutter member is formed of a plate spring.
 10. The push-oncoupling system according to claim 6, wherein the shutter holding memberis provided with a shutter biasing member to bias the shutter member andto dispose the front end of the shutter member at the shield position inthe extension state.